GPX Maker is a quick and easy application to create Aperture, iPhoto, Google Earth, etc. compatible GPS tracks.
This is a solid application built for creating GPX format files. Check to see if the application that you need it for supports GPX files, and then you are all ready to go. Most common nautical, aviation, and handheld GPS units use GPX as the storage format, and most photo geotagging applications expect GPX files.
A few applications do already exist for this purpose, but try them all and compare them for yourself.
GPX Maker uses a complex micro-optimized library with advanced caching and extremely low-level memory management to generate average sized GPX files instantaneously (for extremely large tracks it is still very quick, mere seconds.) It can also reopen and display them just as quickly.
GPX Maker will also not record duplicate coordinates, as this is a waste of space. (e.g. if you are sitting in the exact same place, and the GPS keeps reading the exact same coordinates for a duration, it will not add duplicate coordinates every second, it will only wait until you change locations.) This is completely lossless, but time, space, and processing are saved over other less intelligent recording solutions.
Continued use of GPS running in the background can dramatically decrease battery life.